An impressive body of evidence supports the notion that chemoprevention has the potential to be a major component of control of cancer, including pancreatic cancer, one of the most lethal cancers. We propose to study phospho-valproic acid (P-V), a novel derivative of valproic acid, as an agent for the prevention of pancreatic cancer. P-V inhibits the growth of human cancer cell lines up to 245-fold more potently than VPA. In animal models, P-V is twice as effective against pancreatic cancer as VPA. For example, in xenograft models P-V reduced tumor volume by 68%, compared to control, whereas VPA reduced it by 34% (chemoprevention protocol). Remarkably, when given in combination with cimetidine, a clinically available antiulcer compound, P-V prevented 100% of pancreatic tumors in the same animal model. P-V appears to be safe, as shown by genotoxicity and animal toxicity studies. Its mechanism of action is complex, involving several signaling cascades, most prominently STAT3. Our hypothesis is that P-V 1 cimetidine is an effective and safe chemopreventive agent against pancreatic cancer, acting primarily through the STAT3 pathway. To test this hypothesis, we will pursue the following specific aims: Specific Aim # 1: Determine the chemopreventive efficacy of P-V 1 cimetidine in preclinical models of pancreatic cancer; Specific Aim # 2: Determine the mechanism of action of P-V 1 cimetidine in vitro and in vivo; Specific Aim # 3: Determine the metabolism of P-V 1 cimetidine in cultured pancreatic cancer cells and animals and its safety in animals. At the completion of these studies, we expect to have determined key pharmacological parameters of a promising novel agent and its combination with cimetidine. Given the importance of pancreatic cancer and the lack of effective agents against it, we believe that the proposed work holds the promise of a significant advance in this area.